I don't know what the general agreement is, but from what I have read so far in Jay M. Smith's book Monsters of Gevauden: The Making of a Beast, he explains how different groups really blew the whole incident out of proportion and that in actuality villagers being killed by wild animals was actually not an uncommon occurrence at the time. For example, he brings up the statistic that in the early modern period, the number of human fatalities in France due to wolf attacks could have been as many as 9,000 people.

His explanation for why there were so many killings concentrated around Gevauden is that there probably was a pack of wolves, possibly with rabies, that had lost their fear of humans.

However, Natgeo claim that based off the descriptions there "can be no reasonable doubt" that the beast was in fact a Lion that somehow escaped. The descriptions seem to match that of a subadult male, which would explain why French villagers didn't realize it was a lion as they had probably only ever seen stylized and heraldic images of lions with large manes.

Given the description, reddish fur, dark line along the spine, thin tail with a tassel on the end, large with a bulkier front, the ability to leap and killing it's prey by choking it- it sounds very much like a young and exceptionally violent lion somehow escaped or was released from a private menagerie.

An officer who hunted the beast seemed sure it was a lion.

Other explanations I have read include the possibility that maybe it was a wolf hybrid and/or mastiff. But to me it really seems more like a lion was loose, possibly coupled with separate attacks from existing wolf packs in France.